Some minor bugs still need to be worked out on the new 5000 Series trains before CTA officials give the final go-ahead to Bombardier Transportation to begin production on a total of 706 rail cars covered under several purchase options, CTA President Forrest Claypool said.

The total cost of the 706 cars is $1.137 billion, officials said (this sentence as published has been corrected in this text).

Approval for Bombardier to begin production is expected soon, Claypool said. Thursday's action by the CTA board green-lights the upcoming sale of up to $625 million in bonds to pay for 300 rail cars , interest costs and associated charges. Financing on 406 other cars was completed several years ago.

The CTA board approved a contract for the first 406 cars in May 2006.

Among the new cars' features are aisle-facing seats, alternating current propulsion designed to deliver a smoother ride, electronic maps and destination signs and security-camera systems.

Some riders have complained about the center-facing seats, which CTA officials say will increase the maximum number of people each car can carry.

The new rail cars will replace trains that were manufactured between 1969 and 1978.

The CTA has been testing 10 prototype cars on all eight rail lines since 2009. Deliveries were initially scheduled to start in 2010. It now appears the first cars will arrive next year, officials said, and it will take several years to complete the delivery.

CTA officials said the rail car purchase is a good deal. Interest rates are at historic lows, and the CTA expects to sell bonds at about a 5 percent rate, officials said.

The cost of each rail car comes out to $1.4 million for options the CTA exercised to purchase 300 of the rail cars, said Karen Walker, CTA chief financial officer. The cost was higher per car in the original order of 406 cars. The cost to overhaul existing CTA trains averages $1.2 million per car, she said. (This paragraph as published has been corrected in this text.)

The CTA anticipates maintenance savings of $8 million to $10 million a year, Claypool said.